In industries such as the semi-conductor industry and the photovoltaic industry, silicon is a widely used material. In making silicon chips for semi-conductor devices and silicon wafers for photovoltaic panels, waste silicon is generated which is preferably recovered for re-use since these industries employ an expensive, high purity silicon to start with.
For example, in the photovoltaic industry single crystal ingots of silicon are formed at considerable cost. Silicon ingots are ground to an exact diameter and then sawed into individual wafers for further processing into the final photovoltaic panel. Operations such as grinding, sawing, and the like generate finely subdivided silicon particles which are often suspended in an aqueous medium. For example, ingots of single crystal silicon are cut into wafers using a wafer cooling medium, the water containing one or more detergents to keep the silicon particles from sticking to the saw blade. The result of this type of sawing operation is waste silicon particles of very small size and dispersed in an aqueous medium forming a colloidal solution. This is characterized as a silicon slurry. The silicon particles dispersed in this slurry are high purity particles which are preferably recovered and re-used to make other single crystal ingots, semiconductors, and the like, rather then disposed of as waste.